chassis stiffener

[saracino]

Ciao all
A month or so ago I installed a chassis stiffener and although it certainly has done what it claims since then I get a rather loud resonating sound that comes in at 119kph and disapears at 122kph. The car remains steady and free of any vibration but the passenger and I were taken aback when the loud humming sound showed up at that speed.
Any thoughts?
MIKE

[Gubi]

Is the exhaust clear of the rear cross member?

[SpiderWebb]

Obviously a harmonic vibration. Great idea to check the simple stuff first, like exhaust, exhaust hangars, heat shield, and such. If anything else was touched at the same time, like installing a new trans mount, investigate that as well.
Check the door, dash, trunk, shifter and/or shift boot, center console fit. Maybe when it was installed it stretched another part of the chassis and something is now slightly out of alignment?

Hope you can chase it down easily. Good Luck!

[ecohen2]

I had the same issue... When I installed the frame stiffener the steering box was moved slightly and that caused my alignment to be off. I also had the exhaust system rubbing, but not against the frame. It was above the rear axle and up toward the top of the hump in the muffler portion of the exhaust system. It took forever to figure it out and only occurred at high speeds. It sounded like a very low hum, but you could feel it more than you could hear it.

Ed

[saracino]

The last thing we checked before storing the car in anticipation of a cold Canadian Winter was the exhaust and after some minor adjustments it is clear of front member of the stiffener.The resonating,harmonic sound persists and so we shall put off further trouble shooting till spring. Who knows it may simply fix itself. Thanks for the heads up boys.
Saracino